The present invention relates to filled pneumatic tires and a method of producing the same.
It is known to provide a pneumatic tire casing with a fill to create a flat-proof assembly when fitted to a wheel of a vehicle. One common method is to fill an assembled tire and wheel with a hardening material under pressure that hardens and creates the fill. Once such material is urethane liquid accompanied by a hardening agent.
Urethane filled tires have a number of disadvantages associated therewith. Known methods of filling assembled tires and wheels often require a factory site. Urethane filled tires cannot be employed on vehicles which are to be driven at high speeds, as such results in heat build-up between the rubber tire casing and the urethane fill.
Furthermore, urethane is expensive and has limited reusability when the tire casing is worn out and discarded. Machine operators dislike the rough ride of vehicles having urethane filled tires. Further, filled tires have a high rolling resistance which contributes to the rough ride and results in high fuel consumption. Urethane filled tires are also difficult to retread and, owing to the problem of casing stretching, often loosen at the rim resulting in a loss of pressure.
Where solid vulcanized polymers other than urethane are used as tire fills, similar problems are encountered, especially reversion to liquid when used at high speeds owing to the heat generated between the casing and the fill. The polymer in liquid form can leak from a loose rim or from a cut or puncture in the tire casing. Low density foamed rubber is preferable, if it could maintain its strength at high speeds.
The best known of the presently used tire fill systems is the use of high density foam rubber as illustrated in published U.K. Pat. Application No. 2,164,903A to O""Coin. As is described in this patent, independent concentric rings of high density foam rubber are manufactured and installed in pneumatic tire casings. Although this system works well, there are a number of disadvantages inherent in manufacturing and installing independent concentric rings in pneumatic tire casings. First, due to the vast number of different sizes and shapes of tires, it would be necessary for an installer to carry a huge inventory of rings. Further, the tooling required to produce the vast number of shapes and sizes of concentric rings is extremely expensive. Finally, forming the filler layers in concentric rings hinders their insertion into the pneumatic tire casing.
There are other known filled pneumatic tires, such as my previous designs schematically illustrated in FIGS. 1 and 2. My previous design tire 2 of FIG. 1 has a fill including concentric rings 10, 12 and 14 disposed on a rim 16 and inside a casing 20, shown in its rest state 21. In use, casing 20 heats up and expands to an expanded state 22, rest state 21 being shown in broken line in FIG. 2. Expanded state 22 causes a space or void 30 to develop between outermost ring 14 and casing 20 in its expanded state 22 (FIG. 2).
Additional unillustrated gaps often develop between adjacent concentric rings, and between innermost ring 10 and rim 16.
Rest state 21 of my previous design casing 20 is shown in broken line in FIG. 2. Void 30 leads to even more heat build up between outermost ring 14 and casing 16. The voids between adjacent rings, and between ring 10 and rim 16, likewise cause heat build-up and thus heat deterioration of the rings. Outermost void 30 reduces the puncture-resistance of casing 20.
Thus, there is a need in the industry for a better filled tire which enjoys the advantages of layer fills without the disadvantages thereof.
An object of the invention is to overcome the drawbacks of the known devices.
The principal object of the present invention is to provide a polymeric fill for tires which substantially prevents the development of voids or spaces adjacent fill layers and/or between fill layers and the casing during use.
Another object of the invention is to provide a fill for tires which provides controlled expansion of the fill for ensuring that any gaps or voids which develop between abutting first and second free ends of a layer of fill when the layer of fill expands and the inner diameter of the tire casing expands, in use, do not become so large as to cause undesirable bumping, soft spots, weak spots, and the like, in use.
Another object of the invention is to provide a fill for tires which provides controlled expansion of the fill for ensuring that any configured gaps or voids which develop between abutting first and second free ends of a layer of fill when the layer of fill expands and the inner diameter of the tire casing expands, in use, do not become so large as to cause undesirable bumping, soft spots, weak spots, and the like, in use.
Yet another object of the invention is to provide for the controlled expansion of layered tire fills so that no gaps develop between abutting free ends of filled layers, which gaps are prevented from extending from an outer diameter of the fill to an inner diameter of the fill.
Yet another object of the invention is to provide controlled expansion of a layer of fill that ensures that at least a portion of the thickness of the layer of fill is always provided between the casing and the interior or inner diameter of the layer of fill.
Another object of the invention is to provide tires having a layer of fill with first and second free ends disposed adjacent each other, when installed, and so configured that, in use, at least a portion of the free ends overlap for achieving the above- and below- described objects of the invention.
A further object of the present invention is provide a means of filling many different shapes of tires with a polymeric fill which can be easily made and inserted in large or small shops or in the field with minimal skill and equipment.
Another object of the invention is to provide a puncture-resistant tire which works well at its design carcass operating stretch point.
It is another object of the present invention to provide a polymeric fill for a tire casing which gives a ride comparable to a pneumatic tire but which is puncture-resistant and flat-proof.
A further object of the present invention is to provide a method of manufacturing a variety of fill members that will fit different sizes of casings by providing the polymer fill in a linear strip form to create a layer suitable for insertion as one of a plurality of layers of the fill for a pneumatic tire.
Yet a further object of the present invention is to install the layers of fill such that the total volume of layers making up the fill is substantially equal to the internal volume of the casing.
Still yet another object of the present invention is to provide a simple and inexpensive method of providing a load-bearing filled pneumatic tire.
Still a further object of the present invention is to provide a filled tire capable of performing at higher speeds and/or greater loads than known tires.
It is yet another object of the invention to provide a filled pneumatic tire which has enhanced load-bearing and puncture-resistant qualities both at rest and under severe use conditions.
A further object of the invention is to provide a filled tire in which the layers of fill can be installed and fitted by hand.
It is another object of the invention to provide a filled pneumatic tire having an expandable fill which conforms to the inner diameter of the tire when the tire is in an expanded condition.
It is yet another object of the invention to provide a filled pneumatic tire having controlled expansion of the fill.
These objects and advantages as well as others will be readily apparent from a review of the specification, the claims and the accompanying drawings.
In summary, therefore, the invention is directed to a tire having an expandable fill which conforms to the interior of the tire in its expanded condition.
In one preferred embodiment of the invention a tire includes a casing defining a hollow interior. The casing has an initial inside diameter and an expanded inside diameter. A fill is disposed in the interior of the casing, the fill including a first layer. The first layer has an initial outside diameter substantially the same as the initial inside diameter of the casing for contacting the casing, and the first layer having an expanded outside diameter. The first layer includes first and second free ends, the first free end being disposed substantially adjacent the second free end, and the first and second free ends being substantially freely movable toward and away from each other. A first stepped portion is provided on the first free end substantially adjacent the second free end, and the stepped portion and the second free end being substantially freely movable toward and away from each other. The first stepped portion engages the second free end when the first layer assumes its initial inside diameter. The first and second free ends of the first layer being sufficiently freely movable toward and away from each other so that, when the casing assumes its expanded inside diameter, the first stepped portion of the first layer moves freely away from the second free end of the first layer and defines a first gap therebetween. The first gap being sufficiently large so that the expanded outside diameter of the first layer is sufficiently large to contact the expanded inside diameter of the casing, and the casing is substantially free of space between the first layer and the expanded inside diameter of the casing. The first stepped portion and the second end are configured and contact sufficiently so that the first gap is prevented from extending between the casing to the inside diameter of the first layer.
In another preferred embodiment of the invention, there is provided a tire having a casing defining a hollow interior, a fill disposed in the interior of the casing, and the fill including at least one layer having an initial diameter substantially the same as the initial diameter of the casing. The fill layer includes first and second free ends, the first free end being disposed substantially adjacent the second free end, and the first and second free ends being freely movable relative to each other. When the casing expands and has a final inside diameter, the first free end of the layer moves away from the second free end and defines a gap therebetween, the expansion of the diameter of the layer being sufficient so that the first layer has a final diameter sufficiently large for contacting the casing. In other words, the outer diameter of the first layer contacts the casing.
In another embodiment of the invention, there is provided a tire having a casing defining a hollow interior, a fill disposed in the interior of the casing, and the fill including at least one layer having an initial diameter substantially the same as the initial diameter of the casing. The fill layer includes an expansion joint or gap. When the casing expands the expansion joint expands and causes the first layer to substantially continuously contact the casing.
In other preferred embodiment there is a method of forming a filled tire.
Relative terms, such as up, down, left, and right are for convenience only and are not intended to be limiting.